Mating behavior of the Southern three-banded armadillo (Tolypeutes matacus) in Brazil

Mating systems vary widely among species and populations. Intrasexual and intersexual competition are common. Behavioral, physiological, and morphological traits can influence individual reproductive success. Little is known about the mating biology of the Southern three-banded armadillo Tolypeutes matacus (Desmarest, 1804). This study describes the behavioral repertoire and a physiological trait related to mating of free-ranging armadillos in midwestern Brazil. We captured and marked 58 males (56 adults) and 39 females (33 adults). Female reproductive status was characterized through external morphological traits and 27 of them were radiotracked daily. Mating behaviors were recorded through focal group observations. Four monitored females entered estrus and were recaptured after mating for vulvar characteristics assessment. Estrous females started races and were actively chased by males attempting to mate (events we named rallies). A conditional logistic regression analysis evidenced a positive relationship between body mass and the likelihood of a male winning a ‘rally.’ We observed intense competition and agonistic encounters among males to access receptive females, with up to 14 males around one female in estrus. All four females presented copulatory plugs in the advanced estrous phase. Finally, we observed a female mating with multiple males, indicating a promiscuous mating system.